觀無量壽佛經疏 1.7

1.7

次辯經用。用者力用也，生善滅惡為經力用。滅惡故言力，生善故言用。滅惡故言功，生善故言德。此皆偏舉，具論必備也。苦是惡果，貪恚癡是惡因。惡因不除，果不得謝。是故此經能令五逆罪滅，往生淨土，即是此經之大力用也。

Next, to distinguish the function of the sūtra: function means power and function. Producing goodness and eliminating evil are the power and function of the sūtra. Because it eliminates evil, it is called power; because it produces goodness, it is called function. Because it eliminates evil, it is called efficacy; because it produces goodness, it is called virtue. These are each partial descriptions; a complete explanation must encompass both. Suffering is the fruit of evil; greed, anger, and delusion are the causes of evil. If evil causes are not eliminated, the fruits cannot cease. Therefore, that this sūtra can cause the sins of the five heinous deeds to be extinguished and bring about rebirth in the pure land is precisely the great power and function of this sūtra.